Antimicrobial Resin Compositions

ABSTRACT

Methods for making antimicrobial resins and for forming coatings comprising antimicrobial resins on substrate surfaces are disclosed. The methods involve providing a mixture comprising about 15 weight % to about 80 weight % of a hydrophilic acrylic oligomer, about 10 weight % to about 80 weight % of a multifunctional acrylic monomer, about 5 weight % to about 40 weight % of an adhesion-promoting acrylic or vinyl monomer, and about 0.1 weight % to about 15 weight % of a metal salt; and exposing the mixture to a radiation source to cure at least a portion of the mixture, thereby forming an antimicrobial resin.

BACKGROUND

1. Field of the Disclosure

The disclosure relates generally to antimicrobial resin compositions and methods for making such resins. More particularly, the disclosure is directed to methods of making antimicrobial resin compositions comprising antimicrobial metal salts and methods for forming such resins on substrates, such as medical devices.

2. Brief Description of Related Technology

Even brief exposure to surfaces contaminated with microbes can introduce bacterial, viral, fungal, or other undesirable infections to humans and other animals. Of particular concern is preventing or reducing microbial infection associated with the use of invasive medical devices such as catheters, intravenous fluid administration systems, and similar medical devices which require prolonged patient contact and thus present significant infection risks. Contamination may result from the patients' own flora or from one or more healthcare workers' hands during insertion and/or manipulation of the device, or from both the patient and healthcare worker. Medical devices coated with antimicrobial materials can reduce the transfer of such microbes to patients, thereby improving the safety and efficacy of these devices. Such antimicrobial coatings often include silver metal or silver salts, or other metals with demonstrable antimicrobial activity such as copper, gold, zinc, cerium, platinum, palladium, or tin.

Silver and salts thereof are commonly used in antimicrobial coatings because of their demonstrated broad spectrum antimicrobial activity against various bacteria, viruses, yeast, fungi, and protozoa. It is theorized that the observed antimicrobial activity is primarily due to the ability of silver ions to tightly bind nucleophilic functional groups containing sulfur, oxygen or nitrogen. Many nucleophilic functional groups such as thiols, carboxylates, phosphates, alcohols, amines, imidazoles, and indoles are prevalent in biomolecules. Upon binding of ionized silver to these various nucleophilic functional groups, it is believed that widespread disruption and inactivation of microbial biomolecules (and thus antimicrobial activity) occurs.

Silver and salts thereof have therefore been used as antimicrobial agents in a wide variety of applications; for example, they have been incorporated in the absorbent materials of wound care products such as dressings, gels, and bandages, and also in compositions for providing antimicrobial coatings on medical devices. Polymeric components frequently are added to such silver- or silver salt-containing compositions in order to facilitate manufacturing and/or deposition. One disadvantage of such antimicrobial compositions, however, is their characteristic poor adhesion to substrate surfaces. Strong adhesion to surfaces is frequently desirable to maintain continued release of the antimicrobial agent over a period of time and to avoid loss of the antimicrobial coating by routine contact with a patient or healthcare worker. Many polymer-containing metal or metal salt compositions also exhibit unsatisfactory antimicrobial efficacy profiles. Various factors can contribute to undesirable efficacy profiles, such as poorly dispersed or settled particles of the metal or metal salt, deformation of the coating during curing, or decomposition of the metal or metal salt during subsequent sterilization treatments. Poor dispersion of the metal or metal salt in the composition, for example, can result in heterogeneous release of the metal or metal salt, while a well-dispersed metal or metal salt generally elutes from the composition according to more homogeneous spatial and/or temporal release profiles. Another disadvantage of many polymer-containing metal or metal salt compositions is the heterogeneous crosslinked structure that can result, for example, from long polymer cure times and/or imprecise control of the polymer curing conditions. Long polymer cure times and/or imprecisely controlled polymer curing conditions, for example, can disadvantageously contribute to the formation of poorly dispersed or settled metals or metal salts, and thus can produce compositions having heterogeneous elution profiles.

A disadvantage of antimicrobial compositions comprising metals instead of metal salts is their characteristic color/opaqueness, which prevents a healthcare provider from being able to see through the medical device substrate. Silver coatings, for example, are generally brown in color. Thus, when silver coatings are applied to transparent surfaces, the coated surfaces typically have a brown color and significantly diminished transparency. In contrast to coatings comprising metallic silver, many coatings comprising silver salts are transparent or translucent, and/or lack a colored appearance. Thus, when silver salt coatings are applied to transparent surfaces, the coated surfaces typically have little color and are highly transparent.

SUMMARY

The present disclosure is directed to methods for forming antimicrobial resins. The methods include providing a mixture comprising a hydrophilic acrylic oligomer, a multifunctional acrylic monomer, an adhesion-promoting acrylic or vinyl monomer, and an antimicrobial metal salt; and exposing the mixture to a radiation source to cure at least a portion of the mixture, thereby forming an antimicrobial resin. The methods further include forming medical devices or medical components comprising the antimicrobial resin. In accordance with the present methods, the antimicrobial resin can be applied to a substrate surface to form a coating on the substrate surface. Alternatively, a coating comprising an antimicrobial resin can be formed by providing the mixture on a substrate surface before exposing the mixture to the radiation source.

The substrate surfaces can comprise plastics, glasses, metals, ceramics, elastomers, or mixtures or laminates thereof. The substrate surfaces can comprise surfaces of medical devices or medical device components. Preferred examples of substrate surfaces include polycarbonate medical devices. The substrate surface also can comprise surfaces of medical fluid containers or medical fluid flow systems. Preferred examples of medical fluid flow systems include I.V. sets and components thereof, such as, for example, luer access devices.

The antimicrobial metal salt can comprise various metals or mixtures of metals. Preferred metal salts include salts of silver, copper, gold, zinc, cerium, platinum, palladium, and tin.

The radiation source can be an ultraviolet (UV) light source, an electron beam source, a gamma radiation source, an X-ray source, an ion beam source, a microwave source, a heat source, or other radiation sources.

The hydrophilic acrylic oligomer includes acrylic oligomers and mixtures of acrylic oligomers having one or more acrylate, methacrylate, acrylamide, or methacrylamide functional groups. The hydrophilic acrylic oligomer also includes acrylic oligomers having combinations of the foregoing functional groups.

The multifunctional acrylic monomer includes acrylate esters, methacrylate esters, acrylamides, methacrylamides, and mixtures of the foregoing having more than one acrylate, methacrylate, acrylamide, or methacrylamide functional groups. The multifunctional acrylic monomer also includes acrylic monomers having combinations of the foregoing functional groups.

The adhesion-promoting acrylic or vinyl monomer includes acrylate esters, methacrylate esters, acrylamides, methacrylamides, and mixtures of the foregoing having one or more acrylate, methacrylate, acrylamide, or methacrylamide functional groups. The adhesion-promoting acrylic or vinyl monomer also includes acrylic monomers having combinations of the foregoing functional groups and monomers having vinyl groups.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing the release of silver ions over time from substrate surfaces carrying an antimicrobial resin prepared in accordance with the methods of the disclosure (B-1, B-2, B-3), compared to substrate surfaces carrying antimicrobial resins not prepared in accordance with the methods of the disclosure (A-1, A-2, A-3, C-1, C-2, C-3, D-1, D-2, D-3).

FIG. 2 is a graph showing the total amount of silver released from the samples of FIG. 1 after 96 hours.

FIG. 3 is a graph showing the growth over time in colony forming units (cfu) per mL of S. aureus on a polycarbonate substrate surface carrying a coating comprising a cured antimicrobial resin prepared in accordance with the methods of the disclosure (Sample B), compared to (i) substrate surfaces carrying coatings comprising antimicrobial resins not prepared in accordance with the methods of the disclosure (Sample A, Sample C, and Sample D) and (ii) an uncoated control substrate surface.

DETAILED DESCRIPTION

The present disclosure is directed to methods for forming antimicrobial resins. The methods involve providing a mixture comprising about 15 weight % to about 80 weight % of a hydrophilic acrylic oligomer, about 10 weight % to about 80 weight % of a multifunctional acrylic monomer, about 5 weight % to about 40 weight % of an adhesion-promoting acrylic or vinyl monomer, and about 0.1 weight % to about 15 weight % of an antimicrobial metal salt; and exposing the mixture to a radiation source to cure at least a portion of the mixture, thereby forming an antimicrobial resin. The methods further include forming medical devices or medical components comprising the antimicrobial resin. In accordance with the present methods, the antimicrobial resin can be applied to a substrate surface to form a coating on the substrate surface. In some embodiments, the multifunctional acrylic monomer and the adhesion promoting acrylic or vinyl monomer can be the same compound.

The present disclosure also is directed to methods for forming a coating comprising an antimicrobial resin. The methods involve providing a mixture comprising about 15 weight % to about 80 weight % of a hydrophilic acrylic oligomer, about 10 weight % to about 80 weight % of a multifunctional acrylic monomer, about 5 weight % to about 40 weight % of an adhesion-promoting acrylic or vinyl monomer, and about 0.1 weight % to about 15 weight % of an antimicrobial metal salt; providing the mixture on a substrate surface before exposing the mixture to a radiation source; and exposing the mixture to the radiation source to cure at least a portion of the mixture, thereby forming a coating comprising an antimicrobial resin.

As previously discussed, many polymer-containing metal or metal salt compositions adhere poorly to substrate surfaces and/or exhibit unsatisfactory antimicrobial efficacy profiles. Forming antimicrobial resins according to the methods disclosed herein can advantageously improve the dispersion of the metal salt in the resin composition, prevent settling of the metal salt during the curing process, prevent deformation (e.g., shrinking) of the resin during the curing process, and/or produce more homogeneously crosslinked resins. Accordingly, antimicrobial resins prepared according the methods disclosed herein can display improved efficacy profiles. Furthermore, coatings comprising the antimicrobial resin can display increased adhesion to substrate surfaces. Accordingly, the disclosed methods can provide efficient methods for obtaining medical devices comprising a strongly adherent and/or more efficacious antimicrobial coating and, in general, more efficacious antimicrobial resins.

As described above, many metal-containing compositions are disadvantageously opaque or colored. Irradiation of compositions containing metal salts can reduce the metal salts, thereby producing compositions comprising metals that can give the composition an opaque or colored appearance. Surprisingly, and contrary to the expectations of one of ordinary skill in the art, antimicrobial resins and coatings thereof prepared by radiation curing in accordance with the present disclosure can advantageously be substantially transparent/translucent (upon visual inspection), i.e., generally lacking a colored appearance, despite including ionic metal that one of ordinary skill would expect to be reduced by the radiation used in the curing process, thereby forming the corresponding metal which generally causes the compositions to become colored. Additionally, radiation curing of the antimicrobial resins of the present disclosure can beneficially obviate the need for downstream sterilization processing because the resin can be sterilized by radiation during the curing process.

The substrate surfaces of the present disclosure can comprise various materials including, for example, glasses, metals, plastics, ceramics, and elastomers, as well as mixtures and/or laminates thereof. Suitable examples of plastics include, but are not limited to, acrylonitrile butadiene styrenes, polyacrylonitriles, polyamides, polycarbonates, polyesters, polyetheretherketones, polyetherimides, polyethylenes such as high density polyethylenes and low density polyethylenes, polyethylene terephthalates, polylactic acids, polymethyl methyacrylates, polypropylenes, polystyrenes, polyurethanes, poly(vinyl chlorides), polyvinylidene chlorides, polyethers, polysulfones, silicones, and blends and copolymers thereof. Suitable elastomers include, but are not limited to, natural rubbers, and synthetic rubbers, such as styrene butadiene rubbers, ethylene propylene diene monomer rubbers (EPDM), polychloroprene rubbers (CR), acrylonitrile butadiene rubbers (NBR), chlorosuphonated polyethylene rubbers (CSM), polyisoprene rubbers, isobutylene-isoprene copolymeric rubbers, chlorinated isobutylene-isoprene copolymeric rubbers, brominated isobutylene-isoprene copolymeric rubbers, and blends and copolymers thereof.

In one preferred embodiment of the present disclosure, the antimicrobial resin is formed on (or applied to) a surface of a medical device or medical device component. Medical devices and medical device components which can benefit from the methods according to the disclosure, include, but are not limited to, instruments, apparatuses, implements, machines, contrivances, implants, and components and accessories thereof, intended for use in the diagnosis, cure, mitigation, treatment, or prevention of disease or other condition in humans or other animals, or intended to affect the structure or any function of the body of humans or other animals. Such medical devices are described, for example, in the official National Formulary, the United States Pharmacopoeia, and any supplements thereto. Representative medical devices include, but are not limited to: catheters, such as venous catheters, urinary catheters, Foley catheters, and pain management catheters; dialysis sets; dialysis connectors; stents; abdominal plugs; feeding tubes; indwelling devices; cotton gauzes; wound dressings; contact lenses; lens cases; bandages; sutures; hernia meshes; mesh-based wound coverings; surgical tools; medical monitoring equipment including, but not limited to the touch screen displays often used in conjunction with such equipment; medical pumps; pump housings; gaskets such as silicone O-rings; needles; syringes; surgical sutures; filtration devices; drug reconstitution devices; implants, metal screws, and metal plates. Additional exemplary medical devices include, but are not limited to, medical fluid containers, medical fluid flow systems, infusion pumps, and medical devices such as stethoscopes which regularly come into contact with a patient. One example of a medical fluid flow system is an intravenous fluid administration set, also known as an LV. set, used for the intravenous administration of fluids to a patient. A typical I.V. set uses plastic tubing to connect a phlebotomized subject to one or more medical fluid sources, such as intravenous solutions or medicament containers. I.V. sets optionally include one or more access devices providing access to the fluid flow path to allow fluid to be added to or withdrawn from the IV tubing. Access devices advantageously eliminate the need to repeatedly phlebotomize the subject and allow for immediate administration of medication or other fluids to the subject, as is well known. Access devices can be designed for use with connecting apparatus employing standard luers, and such devices are commonly referred to as “luer access devices,” “luer-activated devices,” or “LADs.” LADs can be modified with one or more features such as antiseptic indicating devices. Various LADs are illustrated in U.S. Pat. Nos. 5,242,432, 5,360,413, 5,730,418, 5,782,816, 6,039,302, 6,669,681, and 6,682,509, and U.S. Patent Application Publication Nos. 2003/0141477, 2003/0208165, 2008/0021381, and 2008/0021392, the disclosures of which are hereby incorporated by reference in their entireties.

I.V. sets can incorporate additional optional components including, for example, septa, stoppers, stopcocks, connectors, protective connector caps, connector closures, adaptors, clamps, extension sets, filters, and the like. Thus, suitable medical devices and medical device components which may be processed in accordance with the methods of the present disclosure include, but are not limited to: I.V. tubing, I.V. fluid bags, I.V. set access devices, septa, stopcocks, I.V. set connectors, I.V. set connector caps, I.V. set connector closures, I.V. set adaptors, clamps, I.V. filters, catheters, needles, stethoscopes, and cannulae. Representative access devices include, but are not limited to: luer access devices including, but not limited to, needleless luer access devices.

The surface of the medical device or medical device component can be fully or partially coated with the antimicrobial resin. The coating can be formed on (or applied to) an exterior surface of the device (i.e., a surface which is intended to come into contact with a patient or healthcare provider), an interior surface of the device (i.e. a surface which is not intended to come into contact with a patient or healthcare provider, but which can come into contact with the patient's blood or other fluids), or both. Suitable medical devices and medical device components are illustrated in U.S. Pat. Nos. 4,412,834, 4,417,890, 4,440,207, 4,457,749, 4,485,064, 4,592,920, 4,603,152, 4,738,668, 5,630,804, 5,928,174, 5,948,385, 6,355,858, 6,592,814, 6,605,751, 6,780,332, 6,800,278, 6,849,214, 6,878,757, 6,897,349, 6,921,390, and 6,984,392, and U.S. Patent Application Publication No. 2007/0085036, the disclosures of which are hereby incorporated by reference in their entireties.

The resins of the present disclosure comprise metal salts having antimicrobial properties. Suitable metal salts for use in the resins include, but are not limited to, salts of silver, copper, gold, zinc, cerium, platinum, palladium, and tin. Antimicrobial resins comprising a combination of two or more of the foregoing metals can also be used.

Hydrophilic Acrylic Oligomers

Antimicrobial resin compositions in accordance with the present disclosure are prepared from a mixture comprising about 15 weight % to about 80 weight % of a hydrophilic acrylic oligomer. Suitable ranges include, but are not limited to, about 25 weight % to about 60 weight %, and/or about 35 weight % to about 50 weight %. The mixture can comprise, for example, about 15 weight % to about 25 weight %, about 25 weight % to about 35 weight %, about 35 weight % to about 45 weight %, about 45 weight % to about 55 weight %, about 55 weight % to about 65 weight %, and/or about 65 weight % to about 80 weight % of the acrylic oligomer. Mixtures including more than one acrylic oligomer also can be used.

In accordance with the present disclosure, the hydrophilic acrylic oligomer can comprise acrylate oligomers, methacrylate oligomers, acrylamide oligomers, methacrylamide oligomers, or mixtures of the foregoing. The acrylic oligomers can be monofunctional oligomers (i.e., oligomers having one acrylate, methacrylate, acrylamide, or methacrylamide group). The acrylic oligomers also can be difunctional oligomers (i.e., oligomers having two acrylate, methacrylate, acrylamide, or methacrylamide groups), trifunctional oligomers (i.e., oligomers having three acrylate, methacrylate, acrylamide, or methacrylamide groups), tetrafunctional oligomers (i.e., oligomers having four acrylate, methacrylate, acrylamide, or methacrylamide groups), pentafunctional oligomers (i.e., oligomers having five acrylate, methacrylate, acrylamide, or methacrylamide groups), or hexafunctional oligomers (i.e., oligomers having six acrylate, methacrylate, acrylamide, or methacrylamide groups). Acrylic oligomers having more than one functional group can comprise the same functional groups or different functional groups. A trifunctional acrylic oligomer, for example, can comprise two acrylate groups and one acrylamide group. A trifunctional acrylic oligomer also can comprise, for example, three acrylate groups. Acrylic oligomers having more than six functional groups (e.g., eight or ten functional groups) and mixtures of the foregoing acrylic oligomers also can be used.

Suitable hydrophilic acrylic oligomers include, but are not limited to: polyepoxy acrylates, polyurethane acrylates, polyester acrylates, polyether acrylates, amine-modified polyether acrylates, polyacrylic acrylates, polycarbonate acrylates, polyepoxy methacrylates, polyurethane methacrylates, polyester methacrylates, polyether methacrylates, amine-modified polyether methacrylates, polyacrylic methacrylates, polycarbonate methacrylates, polyepoxy acrylamides, polyurethane acrylamides, polyester acrylamides, polyether acrylamides, amine-modified polyether acrylamides, polyacrylic acrylamides, polycarbonate acrylamides, polyepoxy methacrylamides, polyurethane methacrylamides, polyester methacrylamides, polyether methacrylamides, amine-modified polyether methacrylamides, polyacrylic methacrylamides, polycarbonate methacrylamides, and mixtures of the foregoing. As discussed above, the foregoing acrylic oligomers include one or more functional groups, for example, one to six functional groups.

Suitable polyepoxy acrylate oligomers include, but are not limited to: aromatic difunctional epoxy acrylates, acrylated oil epoxy acrylates, phenol formaldehyde epoxy acrylates (also known as novolac epoxy acrylates), aliphatic epoxy acrylates, and mixtures of the foregoing.

Exemplary hydrophilic acrylic oligomers include, but are not limited to: ethoxylated bisphenol A diacrylates (e.g., 30 mole ethoxylated bisphenol A diacrylate), ethoxylated bisphenol A dimethacrylates (e.g., 10 mole ethoxylated bisphenol A dimethacrylate), polyethylene glycol diacrylates, polyethylene glycol dimethacrylates, methoxy polyethylene glycol acrylates, methoxy polyethylene glycol methacrylates, polypropylene glycol diacrylates, polypropylene glycol dimethacrylates, methoxy polypropylene glycol acrylates, methoxy polypropylene glycol methacrylates, and mixtures of the foregoing. Ethoxylated acrylates and methacrylates typically include about 4 to about 100 ethoxy groups, for example, about 6 to about 70, about 8 to about 50, about 10 to about 40, and/or about 12 to about 30 ethoxy groups. Oligomers containing polyethylene glycol or polypropylene glycol typically have molecular weights of about 100 g/mol to about 2000 g/mol, for example, about 150 g/mol to about 1000 g/mol, about 200 g/mol to about 800 g/mol, and/or about 300 g/mol to about 600 g/mol.

Multifunctional Acrylic Monomers

Antimicrobial resin compositions in accordance with the present disclosure are prepared from a mixture comprising about 10 weight % to about 80 weight % of a multifunctional acrylic monomer. Suitable ranges include, but are not limited to, about 20 weight % to about 60 weight %, and/or about 30 weight % to about 50 weight %. The mixture can comprise, for example, about 10 weight % to about 20 weight %, about 20 weight % to about 30 weight %, about 30 weight % to about 40 weight %, about 40 weight % to about 50 weight %, about 50 weight % to about 60 weight %, about 60 weight % to about 70 weight %, and/or about 70 weight % to about 80 weight % of the multifunctional acrylic monomer. Mixtures including more than one acrylic monomer also can be used.

In accordance with the present disclosure, the multifunctional acrylic monomer can comprise acrylate esters, methacrylate esters, acrylamides, methacrylamides, or mixtures of the foregoing. The multifunctional acrylic monomers can be difunctional monomers (i.e., monomers having two acrylate, methacrylate, acrylamide, and/or methacrylamide groups). The multifunctional acrylic monomers also can be trifunctional monomers, tetrafunctional monomers, pentafunctional monomers, hexafunctional monomers, or mixtures of the foregoing. Multifunctional acrylic monomers can comprise the same functional groups or different functional groups. A difunctional acrylic monomer, for example, can comprise one acrylate group and one methacrylamide group. A difunctional acrylic monomer also can comprise, for example, two methacrylate groups. Multifunctional acrylic monomers having more than six functional groups (e.g., eight or ten functional groups) and mixtures of the foregoing acrylic monomers also can be used. When exposed to suitable conditions (e.g., a radiation source, optionally in the presence of an initiator), the alkenyl functional groups of the multifunctional acrylic monomers can undergo intermolecular reactions to form, for example, crosslinked structures.

Suitable multifunctional acrylic monomers include, but are not limited to: alkoxylated acrylates; alkoxylated methacrylates; linear, branched, or cyclic alkyl acrylates; linear, branched, or cyclic alkyl methacrylates; linear, branched, or cyclic alkyl acrylamides; linear, branched, or cyclic alkyl methacrylamides; linear, branched, or cyclic alkenyl acrylates; linear, branched, or cyclic alkenyl methacrylates; linear, branched, or cyclic alkenyl acrylamides; linear, branched, or cyclic alkenyl methacrylamides; alkoxylated linear, branched, or cyclic alkyl acrylates; alkoxylated linear, branched, or cyclic alkyl methacrylates; alkoxylated linear, branched, or cyclic alkenyl acrylates; alkoxylated linear, branched, or cyclic alkenyl methacrylates; heterocyclic acrylates; heterocyclic methacrylates; heterocyclic acrylamides; heterocyclic methacrylamides; and mixtures of the foregoing. Difunctional, trifunctional, tetrafunctional, pentafunctional, and hexafunctional derivatives of the foregoing are included.

Alkoxylated multifunctional acrylate monomers typically include about 1 to about 20 alkoxy groups, for example, about 2 to about 10, about 3 to about 8, and/or about 4 to about 6 alkoxy groups. Alkoxy groups include, but are not limited to: methoxy groups, ethoxy groups, and propoxy groups.

Alkyl and alkenyl multifunctional acrylic monomers typically comprise about 4 to about 40 carbon atoms, for example, about 5 to about 21, about 6 to about 18, and/or about 7 to about 15 carbon atoms. The alkyl and alkenyl multifunctional acrylic monomers also can comprise more than 40 carbon atoms. Heterocyclic multifunctional acrylic monomers typically comprise about 5 to about 40 carbon atoms, and one or more heteroatoms such as N, O, or S.

Exemplary multifunctional acrylic monomers include, but are not limited to: 1,12-dodecanediol diacrylate, 1,12-dodecanediol dimethacrylate, 1,3-butylene glycol diacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, alkoxylated cyclohexane dimethanol diacrylates, alkoxylated cyclohexane dimethanol dimethacrylates, alkoxylated hexanediol diacrylates, alkoxylated hexanediol dimethacrylates, alkoxylated neopentyl glycol diacrylates, alkoxylated neopentyl glycol dimethacrylates, cyclohexane dimethanol diacrylate, cyclohexane dimethanol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, dipropylene glycol diacrylate, dipropylene glycol dimethacrylate, ethoxylated bisphenol A diacrylates, ethoxylated bisphenol A dimethacrylates, ethylene glycol diacrylate, ethylene glycol dimethacrylate, neopentyl glycol diacrylate, neopentyl glycol dimethacrylate, polyethylene glycol diacrylates, polyethylene glycol dimethacrylates, propylene glycol diacrylates, propylene glycol dimethacrylates, propoxylated neopentyl glycol diacrylates, propoxylated neopentyl glycol dimethacrylates, tetraethylene glycol diacrylate, tetraethylene glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, tripropylene glycol diacrylate, tripropylene glycol dimethacrylate, ethoxylated trimethylolpropane triacrylates, ethoxylated trimethylolpropane trimethacrylates, propoxylated glyceryl triacrylates, propoxylated glyceryl trimethacrylates, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, propoxylated trimethylolpropane triacrylates, propoxylated trimethylolpropane trimethacrylates, tris(2-hydroxyethyl) isocyanurate triacrylate, tris(2-hydroxyethyl) isocyanurate trimethacrylate, di-trimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate, ethoxylated pentaerythritol tetraacrylates, dipentaerythritol pentaacrylate, pentaerythritol tetraacrylate, and mixtures of the foregoing.

Preferred multifunctional acrylic monomers include 1,3-butylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, and mixtures of the foregoing.

In some embodiments, the multifunctional acrylic monomer and the adhesion-promoting acrylic monomer can be the same.

Adhesion-Promoting Acrylic or Vinyl Monomers

Antimicrobial resin compositions in accordance with the present disclosure are prepared from a mixture comprising about 5 weight % to about 40 weight % of an adhesion-promoting acrylic monomer. Suitable ranges include, but are not limited to, about 10 weight % to about 35 weight %, and/or about 15 weight % to about 30 weight %. The mixture can comprise, for example, about 5 weight % to about 10 weight %, about 10 weight % to about 15 weight %, about 15 weight % to about 20 weight %, about 20 weight % to about 25 weight %, about 25 weight % to about 30 weight %, about 30 weight % to about 35 weight %, and/or about 35 weight % to about 40 weight % of the adhesion-promoting acrylic monomer. Mixtures including more than one adhesion-promoting acrylic monomer also can be used.

In accordance with the present disclosure, the adhesion-promoting acrylic monomer can comprise acrylate esters, methacrylate esters, acrylamides, methacrylamides, or mixtures of the foregoing. The adhesion-promoting acrylic monomers can be monofunctional monomers (i.e., monomers having one acrylate, methacrylate, acrylamide, or methacrylamide group). The adhesion-promoting acrylic monomers also can be difunctional monomers, trifunctional monomers, tetrafunctional monomers, pentafunctional monomers, hexafunctional monomers, or mixtures of the foregoing. Adhesion-promoting acrylic monomers having more than one functional group can comprise the same functional groups or different functional groups. A difunctional adhesion-promoting acrylic monomer, for example, can comprise one acrylate group and one methacrylamide group. A difunctional adhesion-promoting acrylic monomer also can comprise, for example, two methacrylate groups. Adhesion-promoting acrylic monomers having more than six functional groups (e.g., eight or ten functional groups) and mixtures of the foregoing adhesion-promoting acrylic monomer s also can be used.

In some embodiments, the adhesion-promoting acrylic monomer can be the same as the multifunctional acrylic monomer.

Adhesion-promoting acrylic or vinyl monomers can be hydrophilic or hydrophobic. Hydrophilic monomers can advantageously provide increased hydrophilicity to the resin composition. Suitable hydrophilic monomers can comprise, for example, pendent hydrophilic groups such as alcohols, amines, thiols, carboxylates, phosphates, and sulfates. Exemplary hydrophilic monomers include, but are not limited to, 1,3-butylene glycol diacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, and 2-(2-ethoxyethoxy)ethyl acrylate.

Suitable adhesion-promoting acrylic monomers include, but are not limited to: alkoxylated acrylates; alkoxylated methacrylates; linear, branched, or cyclic alkyl acrylates; linear, branched, or cyclic alkyl methacrylates; linear, branched, or cyclic alkyl acrylamides; linear, branched, or cyclic alkyl methacrylamides; linear, branched, or cyclic alkenyl acrylates; linear, branched, or cyclic alkenyl methacrylates; linear, branched, or cyclic alkenyl acrylamides; linear, branched, or cyclic alkenyl methacrylamides; alkoxylated linear, branched, or cyclic alkyl acrylates; alkoxylated linear, branched, or cyclic alkyl methacrylates; alkoxylated linear, branched, or cyclic alkenyl acrylates; alkoxylated linear, branched, or cyclic alkenyl methacrylates; heterocyclic acrylates; heterocyclic methacrylates; heterocyclic acrylamides; heterocyclic methacrylamides; caprolactone acrylates; caprolactone methacrylates; caprolactam acrylamides; caprolactam methacrylamides; valerolactone acrylates; valerolactone methacrylates; valerolactam acrylamides; valerolactam methacrylamides; butyrolactone acrylates; butyrolactone methacrylates; butyrolactam acrylamides; butyrolactam methacrylamides; propiolactone acrylates; propiolactone methacrylates; propiolactam acrylamides; propiolactam methacrylamides; acrylic acid; and mixtures of the foregoing. Monofunctional, difunctional, trifunctional, tetrafunctional, pentafunctional, and hexafunctional derivatives of the foregoing also are included.

Alkoxylated adhesion-promoting acrylic monomers typically include about 1 to about 20 alkoxy groups, for example, about 2 to about 10, about 3 to about 8, and/or about 4 to about 6 alkoxy groups. Alkoxy groups include, but are not limited to: methoxy groups, ethoxy groups, and propoxy groups.

Alkyl and alkenyl adhesion-promoting acrylic monomers typically comprise about 4 to about 40 carbon atoms, for example, about 5 to about 21, about 6 to about 18, and/or about 7 to about 15 carbon atoms. The alkyl and alkenyl adhesion-promoting acrylic monomers also can comprise more than 40 carbon atoms. Heterocyclic adhesion-promoting acrylic monomers typically comprise about 5 to about 40 carbon atoms, and one or more heteroatoms such as N, O, or S.

Caprolactone, valerolactone, butyrolactone, and propiolactone acrylate monomers typically comprise about 1 to about 10 caprolactone, valerolactone, butyrolactone, or propiolactone groups, for example, about 2 to about 8 and/or about 3 to about 6 groups. Caprolactam, valerolactam, butyrolactam, and propiolactam acrylamide monomers typically comprise about 1 to about 10 caprolactam, valerolactam, butyrolactam, or propiolactam groups, for example, about 2 to about 8 and/or about 3 to about 6 groups.

Exemplary adhesion-promoting acrylic monomers include, but are not limited to: acrylic acid, methacrylic acid, 2-(2-ethoxyethoxy)ethyl acrylate, 2-(2-ethoxyethoxy)ethyl methacrylate, 2-phenoxyethyl acrylate, 2-phenoxyethyl methacrylate, 3,3,5-trimethylcyclohexyl acrylate, 3,3,5-trimethylcyclohexyl methacrylate, alkoxylated lauryl acrylates, alkoxylated lauryl methacrylates, alkoxylated phenol acrylates, alkoxylated phenol methacrylates, alkoxylated tetrahydrofurfuryl acrylates, alkoxylated tetrahydrofurfuryl methacrylates, lauryl acrylate, lauryl methacrylate, cyclic trimethylolpropane formal acrylate, cyclic trimethylolpropane formal methacrylate, dicyclopentadienyl acrylate, dicyclopentadienyl methacrylate, diethylene glycol methyl ether acrylate, diethylene glycol methyl ether methacrylate, ethoxylated hydroxyethyl acrylates, ethoxylated hydroxyethyl methacrylates, ethoxylated nonyl phenol acrylates, ethoxylated nonyl phenol methacrylates, isobornyl acrylate, isobornyl methacrylate, isodecyl acrylate, isodecyl methacrylate, isoocyl acrylate, isoocyl methacrylate, metallic acrylates, metallic methacrylates, methoxy polyethylene glycol acrylates, methoxy polyethylene glycol methacrylates, octyldecyl acrylate, octyldecyl methacrylate, polypropylene glycol acrylates, polypropylene glycol methacrylates, propoxylated allyl acrylates, propoxylated allyl methacrylates, stearyl acrylate, stearyl methacrylate, tetrahydrofurfuryl acrylate, tetrahydrofurfuryl methacrylate, tridecyl acrylate, tridecyl methacrylate, triethylene glycol ethyl ether acrylate, triethylene glycol ethyl ether methacrylate, 1,12-dodecanediol diacrylate, 1,12-dodecanediol dimethacrylate, 1,3-butylene glycol diacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, alkoxylated cyclohexane dimethanol diacrylates, alkoxylated cyclohexane dimethanol dimethacrylates, alkoxylated hexanediol diacrylates, alkoxylated hexanediol dimethacrylates, alkoxylated neopentyl glycol diacrylates, alkoxylated neopentyl glycol dimethacrylates, cyclohexane dimethanol diacrylate, cyclohexane dimethanol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, dipropylene glycol diacrylate, dipropylene glycol dimethacrylate, ethoxylated bisphenol A diacrylates, ethoxylated bisphenol A dimethacrylates, ethylene glycol diacrylate, ethylene glycol dimethacrylate, neopentyl glycol diacrylate, neopentyl glycol dimethacrylate, polyethylene glycol diacrylates, polyethylene glycol dimethacrylates, propylene glycol diacrylates, propylene glycol dimethacrylates, propoxylated neopentyl glycol diacrylates, propoxylated neopentyl glycol dimethacrylates, tetraethylene glycol diacrylate, tetraethylene glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, tripropylene glycol diacrylate, tripropylene glycol dimethacrylate, ethoxylated trimethylolpropane triacrylates, ethoxylated trimethylolpropane trimethacrylates, propoxylated glyceryl triacrylates, propoxylated glyceryl trimethacrylates, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, propoxylated trimethylolpropane triacrylates, propoxylated trimethylolpropane trimethacrylates, tris(2-hydroxyethyl) isocyanurate triacrylate, tris(2-hydroxyethyl) isocyanurate trimethacrylate, di-trimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate, ethoxylated pentaerythritol tetraacrylates, dipentaerythritol pentaacrylate, pentaerythritol tetraacrylate, and mixtures of the foregoing.

Exemplary adhesion-promoting acrylic monomers also include, but are not limited to: 3,3,5-trimethylcyclohexyl acrylamide, 3,3,5-trimethylcyclohexyl methacrylamide, dicyclopentadienyl acrylamide, dicyclopentadienyl methacrylamide, isobornyl acrylamide, isobornyl methacrylamide, isodecyl acrylamide, isodecyl methacrylamide, isoocyl acrylamide, isoocyl methacrylamide, octyldecyl acrylamide, octyldecyl methacrylamide, stearyl acrylamide, stearyl methacrylamide, tetrahydrofurfuryl acrylamide, tetrahydrofurfuryl methacrylamide, tridecyl acrylamide, tridecyl methacrylamide, dimethyl acrylamide, dimethyl methacrylamide, and mixtures of the foregoing.

Preferred adhesion-promoting acrylic monomers include acrylic acid, N,N-dimethyl acrylamide, 1,3-butylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 2-hydroxyethyl methacrylate, 4-hydroxybutyl acrylate, tetrahydrofurfuryl acrylate, 2-(2-ethoxyethoxy)ethyl acrylate, and mixtures of the foregoing.

Adhesion-promoting vinyl monomers include, for example, N-vinyl pyrrolidone.

Antimicrobial Metal Salts

Antimicrobial resin compositions in accordance with the present disclosure are prepared from a mixture comprising about 0.1 weight % to about 15 weight % of an antimicrobial metal salt. Suitable ranges include, but are not limited to, about 0.5 weight % to about 10 weight %, and/or about 1 weight % to about 8 weight %. The mixture can comprise, for example, about 0.1 weight % to about 1 weight %, about 1 weight % to about 5 weight %, about 5 weight % to about 10 weight %, and/or about 10 weight % to about 15 weight % of the metal salt. Mixtures including more than one metal salt also can be used.

In accordance with the present disclosure, the antimicrobial metal salt can comprise metal salts including, but not limited to, salts of silver, copper, gold, zinc, cerium, platinum, palladium, tin, and mixtures of the foregoing. Mixtures of metals salts also can be used. Suitable metal salts include, but are not limited to metal sulfadiazines, metal halides (e.g., metal fluorides, metal chlorides, metal bromides, metal iodides), metal acetates, metal hydroxides, metal carbonates, metal oxalates, metal phosphates, metal sulfates, metal chlorates, metal bromates, metal iodates, and mixtures of the foregoing. Exemplary metal salts include, but are not limited to, silver salts, such as silver sulfadiazine, silver halides (e.g., silver fluoride, silver chloride, silver bromide, silver iodide), silver acetate, silver hydroxide, silver carbonate, silver oxalate, silver phosphate, silver sulfate, silver chlorate, silver bromate, silver iodate, and mixtures of the foregoing.

The metal salt in accordance with the present disclosure can comprise particles, such as microparticles or nanoparticles. The metal salt particles typically have a diameter in the range of about 1 nanometer to about 50 micrometers, for example, from about 10 nanometers to about 25 micrometers, from about 50 nanometers to about 10 micrometers, and/or from about 100 nm to about 1 micrometer.

Initiators

Antimicrobial resin compositions in accordance with the present disclosure optionally can be prepared from a mixture comprising about 0.1 weight % to about 15 weight % of an initiator. Suitable ranges include, but are not limited to, about 0.5 weight % to about 10 weight %, and/or about 1 weight % to about 8 weight %. The mixture can comprise, for example, about 0.1 weight % to about 1 weight %, about 1 weight % to about 5 weight %, about 5 weight % to about 10 weight %, and/or about 10 weight % to about 15 weight % of the initiator. Mixtures including more than initiator also can be used.

Suitable initiators include, but are not limited to: α-hydroxyketones, phenylglyoxylates, benzyldimethyl ketals, α-aminoketones, mono acyl phosphines, bis acyl phosphines, phosphine oxides, metallocenes (e.g., fluorinated diaryl titanocenes such as IRGACURE® 784), iodonium salts, mercaptobenzothiazoles, mercptobenzooxazoles, benzophenones, acetophenones, benzoin alkyl ethers, hexaarylbisimidazoles, and mixtures thereof.

Exemplary photoinitiators include, but are not limited to: 1-hydroxycyclohexyl phenyl ketone, benzophenone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone, methylbenzoylformate, oxy-phenyl-acetic acid 2-[2-oxo-2-phenyl-acetoxy-ethoxy]-ethyl ester, oxy-phenyl-acetic acid 2-[2-hydroxy-ethoxy]-ethyl ester, α,α-dimethoxy-α-phenylacetophenone, 2-benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone, 2-methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone, diphenyl (2,4,6-trimethylbenzoyl)-phosphine oxide, phenyl bis(2,4,6-trimethyl benzoyl) phosphine oxide, bis(η⁵-2,4-cyclopentadien-1-yl) bis[2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl]titanium, (4-methylphenyl)-[4-(2-methylpropyl)phenyl]-iodonium hexafluorophosphate, 2,2-dimethoxy-1,2-diphenylethan-1-one, 2,4,6-trimethylbenzoyldiphenylphosphine oxide (LUCIRIN TPO®), and mixtures of the foregoing.

Additional suitable initiators include, but are not limited to: azobisbutyronitrile and dibenzoyl peroxides.

Additives

The antimicrobial resin formulations optionally comprise one or more additives. Suitable additives include, but are not limited to: photoinitiators (e.g., benzophenone and pyruvic acid), stabilizers, chain transfer agents, plasticizers, light stabilizers, UV screening compounds, leveling agents, wetting agents, preservatives, adhesion promoters, emulsifiers, pigments, dyes (e.g., eosin, methylene blue, and ketocumarines), or fillers. The optional additives typically comprise about 0.1 weight % to about 20 weight % of the formulations, for example, about 0.5 weight % to about 15 weight %, about 1 weight % to about 10 weight %, and/or about 2 weight % to about 5 weight %.

The additive can comprise saturated fatty acids, unsaturated fatty acids, or mixtures thereof. Fatty acids can advantageously stabilize silver salt dispersions, thereby maintaining the silver salt in a highly dispersed state during the curing step. Suitable fatty acids include, but are not limited to: decanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, eicosanoic acid, docsanoic acid, tetracosanoic acid, α-linolenic acid, stearidonic acid, eicosapentaenoic acid, docosahexaenoic acid, linoleic acid, γ-linolenic acid, dihomo-γ-linolenic acid, arachidonic acid, oleic acid, erucic acid, nervonic acid, or mixtures of the foregoing. Quaternary ammonium compounds also can provide stabilization of silver salt dispersions.

Suitable fillers for the formulations according to the disclosure include, for example, polymers soluble in the reactive acrylic monomers, such as polyvinyl alcohol and polyvinyl butyrate.

Antimicrobial Resins

The antimicrobial resins of the present disclosure are formed by providing a mixture comprising one or more hydrophilic acrylic oligomers, one or more multifunctional acrylic monomers, one or more adhesion-promoting acrylic or vinyl monomers, and one or more antimicrobial metal salts; and exposing the mixture to a radiation source. Exposure of the mixture to the radiation source cures at least a portion of the mixture. Combining the aforementioned components and exposing same to radiation provides more efficacious antimicrobial resins, as previously discussed. Additionally, the components have been selected so that the formed resin is hydrophilic and has hydrogel-like properties such that it is compatible with biological tissues. Hydrophilicity advantageously can promote continuous and rapid release of the antimicrobial metal salt from the resin into aqueous solution. Furthermore, the antimicrobial resins of the present disclosure comprise components that advantageously promote the stabilization of metal salt dispersions, thereby facilitating the preparation of more homogeneously dispersed resins comprising difficult to disperse metal salts (e.g., silver sulfadiazine). As previously discussed, more homogeneously dispersed metal salts can have improved efficacy and/or more desirable elution profiles.

The radiation source can comprise an ultraviolet (UV) light source, an electron beam source, a gamma radiation source, a X-ray source, an ion beam source, a microwave source, a heat source, or a combination of the foregoing. Generally where electron beam radiation is used, the amount can be from about 1 to about 10 Mrads, for example, from about 3 to about 8 Mrads. Where a UV light source is used, the radiation amount can be from about 0.1 J/cm² to about 5 J/cm².

In accordance with the methods of the present disclosure, the antimicrobial resins can be formed on a substrate surface by providing a mixture comprising one or more hydrophilic acrylic oligomers, one or more multifunctional acrylic monomers, one or more adhesion-promoting acrylic or vinyl monomers, and one or more metal salts, providing the mixture on the substrate surface, and exposing the mixture to a radiation source. The mixture can be provided on the substrate surface by various manual and mechanical means of application, for example, by spreading, layering, dipping, coating, swabbing, spraying, pouring, and/or washing. Prior to providing the mixture on the substrate surface, the mixture typically has a viscosity of about 50 centipoise (cP) to about 1000 cP, for example, about 100 cP to about 800 cP, about 200 cP to about 600 cP, and/or about 300 cP to about 500 cP, but higher and lower viscosities also can be used.

The antimicrobial resins in accordance with the present disclosure comprise about 15 weight % to about 80 weight % of hydrophilic acrylic oligomer units, about 10 weight % to about 80 weight % of multifunctional acrylic monomer units, about 5 weight % to about 40 weight % of adhesion-promoting acrylic or vinyl monomer units, and about 0.1 weight % to about 15 weight % of an antimicrobial metal salt. The hydrophilic acrylic oligomer units, the multifunctional acrylic monomer units, and the adhesion-promoting acrylic or vinyl monomer units of the antimicrobial resins are typically substantially cured, or cross-linked, after exposure to radiation.

The present disclosure also is directed to an antimicrobial resin composition prepared by a process comprising: providing a mixture comprising about 15 weight % to about 80 weight % of a hydrophilic acrylic oligomer, about 10 weight % to about 80 weight % of a multifunctional acrylic monomer, about 5 weight % to about 40 weight % of an adhesion-promoting acrylic or vinyl monomer, and about 0.1 weight % to about 15 weight % of an antimicrobial metal salt; and exposing the mixture to a radiation source to cure at least a portion of the mixture, thereby forming an antimicrobial resin.

The disclosure may be better understood by reference to the following examples which are not intended to be limiting, but rather only set forth exemplary embodiments in accordance with the disclosure.

EXAMPLES Example 1 Preparation of Antimicrobial Resins on Polycarbonate Surfaces

An antimicrobial resin was prepared by combining SR 610 polyethylene glycol diacrylate (23.63 weight %), CD9038 ethoxylated bisphenol A diacrylate (28.35 weight %), acrylic acid (9.45 weight %), dimethyl acrylamide (9.45 weight %), SR 238 hexanediol diacrylate (9.45 weight %), 2-hydroxyethyl methacrylate (9.45 weight %), stearic acid (0.50 weight %), and silver sulfadiazine (5.00 weight %). IRGACURE® 651 α,α-dimethoxy-α-phenylacetophenone initiator (4.72 weight %) was added, and the resulting mixture was applied to a polycarbonate surface. The polycarbonate surface was then exposed to a UV light source (approximately 0.5 J/cm²) to cure the mixture, thereby forming a coating comprising an antimicrobial resin on the polycarbonate surface. The cured antimicrobial resin adhered strongly to the polycarbonate surface.

Component Weight % Function Supplier IRGACURE ® 651 (α,α- 4.72 Initiator Ciba dimethoxy-α- phenylacetophenone) SR 610 (polyethylene 23.63 Oligomer/ Sartomer glycol-600 diacrylate) monomer CD 9038 (30 mole ethoxylated 28.35 Oligomer Sartomer bisphenol A diacrylate) Acrylic acid 9.45 Monomer Aldrich Dimethyl acrylamide 9.45 Monomer Aldrich SR 238 (1,6-hexanediol 9.45 Monomer Sartomer diacrylate) 2-Hydroxyethyl methacrylate 9.45 Monomer Aldrich Silver sulfadiazine 5.00 Antimicrobial Aldrich agent Stearic acid 0.50 Emulsifier Aldrich

The antimicrobial resin formed after UV curing was observed to be hydrophilic, and rapidly increased in weight due to the absorption of water (data not shown). Hydrophilicity advantageously can promote continuous and rapid release of the antimicrobial metal salt from the resin into aqueous solution.

The elution profile of silver ions released from the antimicrobial resin was tested by placing the polycarbonate surface carrying the antimicrobial resin in aqueous solution and detecting silver ion levels. An initial burst of silver ions was released within approximately 30 minutes of the start of the measurements. After the initial burst, the release of silver ions declined slightly, stabilizing at about 50 minutes after the start of the experiment (see FIG. 1, Sample B) and providing sustained release of a relatively high concentration of silver for at least 48 hours. High total amounts of silver ion were released over 96 hours by the antimicrobial resin prepared in accordance with the disclosed methods (see FIG. 2, Sample B). In contrast, coatings of approximately the same thicknesses prepared from formulations not in accordance with the disclosure released lower overall levels of silver (see FIG. 2, Samples C and D), and did not exhibit sustained release of a relatively high concentration of silver ions (see FIG. 1, Samples A, C, and D). The coating of comparative Sample A included a silver-containing polyvinyl alcohol hydrogel layer prepared in accordance with the disclosure of U.S. Patent Publication No. 2008/0063693. The coating of comparative Sample C included silver nanoparticles and a stabilizing agent and was prepared in accordance with the disclosure of U.S. Patent Publication No. 2007/0003603. The coating of comparative Sample D was prepared by blending 8% ALPHA-SAN® antimicrobial silver additive (available from Milliken & Company, Spartanburg, S.C.) in MAKROLON® Rx-1805 medical grade polycarbonate resin (available from Bayer MaterialsScience, Pittsburgh, Pa.) and applying the coating to a substrate surface.

Example 2 Antimicrobial Activity of Radiation-Cured Resins

The antimicrobial resin-carrying polycarbonate surface prepared in Example 1 was tested to determine its ability to inhibit growth of microorganisms. Polycarbonate surfaces carrying coatings comprising antimicrobial resins not in accordance with the disclosure (see Example 1) and an uncoated polycarbonate surface were also tested. A suspension of Staphylococcus aureus (S. aureus) was grown in tryptic soy broth for 18-24 hours. The suspension was then diluted in saline to 6.4×10⁵ colony-forming units per mL (cfu/mL). Tubes containing 5 mL saline were inoculated with 0.1 mL (6.4×10⁴ cfu) of the suspension. Samples A-D and an uncoated polycarbonate surface were aseptically added to the tubes, which were incubated at 20-25° C. for 48 hours. The samples then were plated in tryptic soy agar in triplicate and incubated at 30-35° C. for 48 hours. After this time, growth of S. aureus was measured, as shown in FIG. 3. The antimicrobial resin prepared in accordance with the disclosure (see FIG. 3, Sample B) displayed about 10-fold improved antimicrobial activity 96 hours after treatment with S. aureus, compared to the antimicrobial resins not prepared in accordance with the disclosed methods (see FIG. 3, Samples A, C and D) and the uncoated polycarbonate surface (see FIG. 3, Control). 

1.-32. (canceled)
 33. An antimicrobial resin composition comprising: about 15 weight % to about 80 weight % of hydrophilic acrylic oligomer units; about 10 weight % to about 80 weight % of multifunctional acrylic monomer units; about 5 weight % to about 40 weight % of monofunctional adhesion-promoting acrylic or vinyl monomer units; and about 0.1 weight % to about 15 weight % of an antimicrobial metal salt; wherein the hydrophilic acrylic oligomer units, the multifunctional acrylic monomer units, and the monofunctional adhesion-promoting acrylic or vinyl monomer units are substantially cured.
 34. An antimicrobial resin composition prepared by the process comprising: providing a mixture comprising about 15 weight % to about 80 weight % of a hydrophilic acrylic oligomer, about 10 weight % to about 80 weight % of a multifunctional acrylic monomer, about 5 weight % to about 40 weight % of a monofunctional adhesion-promoting acrylic or vinyl monomer, and about 0.1 weight % to about 15 weight % of an antimicrobial metal salt; and exposing the mixture to a radiation source to cure at least a portion of the mixture, thereby forming an antimicrobial resin.
 35. The composition of claim 33, wherein the hydrophilic acrylic oligomer comprises monofunctional oligomers, difunctional oligomers, trifunctional oligomers, tetrafunctional oligomers, pentafunctional oligomers, hexafunctional oligomers, or mixtures thereof.
 36. The composition of claim 33, wherein the hydrophilic acrylic oligomer comprises polyepoxy acrylates, polyurethane acrylates, polyester acrylates, polyether acrylates, amine-modified polyether acrylates, polyacrylic acrylates, polycarbonate acrylates, polyepoxy methacrylates, polyurethane methacrylates, polyester methacrylates, polyether methacrylates, amine-modified polyether methacrylates, polyacrylic methacrylates, polycarbonate methacrylates, polyepoxy acrylamides, polyurethane acrylamides, polyester acrylamides, polyether acrylamides, amine-modified polyether acrylamides, polyacrylic acrylamides, polycarbonate acrylamides, polyepoxy methacrylamides, polyurethane methacrylamides, polyester methacrylamides, polyether methacrylamides, amine-modified polyether methacrylamides, polyacrylic methacrylamides, polycarbonate methacrylamides, or mixtures thereof.
 37. The composition of claim 33, wherein the hydrophilic acrylic oligomer comprises ethoxylated bisphenol A diacrylates, polyethylene glycol diacrylates, or mixtures thereof.
 38. The composition of claim 33, wherein the multifunctional acrylic monomer comprises acrylate esters, methacrylate esters, acrylamides, methacrylamides, or mixtures thereof.
 39. The composition of claim 33, wherein the multifunctional acrylic monomer comprises difunctional monomers, trifunctional monomers, tetrafunctional monomers, pentafunctional monomers, hexafunctional monomers, or mixtures thereof.
 40. The composition of claim 33, wherein the multifunctional acrylic monomer comprises 1,3-butylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, or mixtures thereof.
 41. The composition of claim 33, wherein the monofunctional adhesion-promoting acrylic or vinyl monomer comprises acrylate esters, methacrylate esters, acrylamides, methacrylamides, or mixtures thereof.
 42. The composition of claim 33, wherein the monofunctional adhesion-promoting acrylic or vinyl monomer comprises acrylic acid, N,N-dimethyl acrylamide, 2-hydroxyethyl methacrylate, 4-hydroxybutyl acrylate, tetrahydrofurfuryl acrylate, 2-(2-ethoxyethoxy)ethyl acrylate, N-vinyl pyrrolidone, or mixtures thereof.
 43. The composition of claim 33, wherein the metal salt comprises a metal selected from the group consisting of silver, copper, gold, zinc, cerium, and mixtures thereof.
 44. The composition of claim 33, wherein the metal salt comprises silver.
 45. The composition of claim 33, wherein the metal salt comprises silver sulfadiazine.
 46. The composition of claim 33, wherein the metal salt comprises particles having a diameter of about 1 nanometer to about 50 micrometers.
 47. The composition of claim 33, wherein the metal salt comprises silver sulfadiazine particles.
 48. The composition of claim 33, further comprising a saturated fatty acid, an unsaturated fatty acid, or a mixture thereof.
 49. The composition of claim 33, further comprising a fatty acid selected from the group consisting of: decanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, eicosanoic acid, docsanoic acid, tetracosanoic acid, α-linolenic acid, stearidonic acid, eicosapentaenoic acid, docosahexaenoic acid, linoleic acid, γ-linolenic acid, dihomo-γ-linolenic acid, arachidonic acid, oleic acid, erucic acid, nervonic acid, and mixtures thereof.
 50. The composition of claim 33, wherein hydrophilic acrylic oligomer is selected from the group consisting of difunctional oligomers, trifunctional oligomers, tetrafunctional oligomers, pentafunctional oligomers, hexafunctional oligomers, and mixtures thereof, and wherein the multifunctional acrylic monomer is selected from the group consisting of alkyl multifunctional monomers and alkenyl multifunctional monomers.
 51. The composition of claim 34, wherein the radiation source comprises an ultraviolet (UV) light source, an electron beam source, a gamma radiation source, an X-ray source, an ion beam source, a microwave source, a heat source, or a combination of the foregoing.
 52. The composition of claim 34, wherein the mixture further comprises about 0.1 weight % to about 15 weight % of an initiator. 